1. Field of the Invention
The system and method of the present invention relates generally to sewer cleaning and in particular to cleaning and removal of solid materials from city sewers.
2. Description of the Related Technology
Sewers must be cleaned periodically in order to maintain proper sewage flow and capacity. Cleaning removes sand and other deleterious materials that have infiltrated into the sewer as well as solid materials that have settled out from the normally slow moving waste slurry that varies in volume and flow rate depending on the collective amount of effluents emptied into the sewer system over time. In order to properly clean the vast lengths of sewer lines in a typical city, an efficient and cost effective method of cleaning must be employed that can handle the large volume of material that must be removed from a typical sewer line.
Typically, a commercial sewer cleaning operation uses truck-mounted equipment for pumping high pressure wash water through the sewer being cleaned and collection of the resulting solid waste material. A truck-mounted sewer cleaning system comprises a water jet router normally located at the front of the truck and a vacuum system and tank located at the rear of the truck.
The water jet router is made up of a high pressure water pump feeding pressurized wash water through a hose having a cleaning head on its end. This cleaning head has water nozzles on its back face which creates a jet action resulting from the high pressure water flowing out the nozzles. The high pressure water jet action both washes the downstream sewer pipe and propels the cleaning head upstream for continuous washing action of the entire length of sewer pipe being cleaned. The position of the cleaning head and its rate of forward travel is regulated by control of the hose reel integrally mounted on the washing truck.
A second hose is lowered into a manhole downstream of the cleaning head and is in communication with the resulting water slurry produced from the washing action. This hose is connected to a vacuum system which lifts the water slurry and all contained debris up from the bottom of the manhole into a vacuum holding tank mounted on the rear of the wash truck. Thus, the high pressure wash water brings the solid materials suspended in water to the manhole and the vacuum action picks up the waste material and deposits it into the truck-mounted holding container.
The materials contained within this vacuum container must be removed when the container is full. Typically, this waste is discarded at a dump or landfill. Because the vacuum container normally is mounted on a vacuum wash truck, sewer cleaning operations must be suspended until the container is emptied. Depending on the distance from the dump site to the sewers being washed, several hours may be lost due to dumping collected solids. In addition, a great deal of water remains in the vacuum tank along with the solids because the vacuum system typically picks up only a small fraction of the solids by volume of water. Typically, industry practice tries to keep wash water flow at a minimum when using the vacuum method of sewer cleaning so that the vacuum holding container does not fill up mostly with spent wash water. Whatever fills up the vacuum container must be disposed of. Therefore, the operator must pay expensive landfill prices to dispose of the spent work water and must obtain additional work water.